Zeroth law of thermodynamics is concerned with thermal equilibrium. It is the basis for all thermometry (the measurement of temperature). It also helps in comparing temperatures of two bodies with the help of third body taken as reference.This law was enunciated by R.H. Fowler in the year 1931. In fact without zeroth law of thermodynamics first and second laws cannot exist.But the necessity of this law recognized after giving the statements of first and second laws. To give priority to this law it is designated as zeroth law of thermodynamics.
Also Read :- Types of patterns
Zeroth law of thermodynamics.
“It states that when two bodies are in thermal equilibrium with a third body, they are in thermal equilibrium with each other and hence are at the same temperature”.
If the bodies A and B are in thermal equilibrium with body C then A and B must be in thermal equilibrium with each other. Zeroth law implies that the bodies A,B and C will be at the same temperature. The limitation of zeroth law is that it cannot be derived from other laws and cannot be applicable for other kinds of equilibrium i.e, It is only applicable for thermal equilibrium.